AD 77-16-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus Helicopters Deutschland GmbH | BO-105A | Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | BO-105C | Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters |
Unsafe Condition
Excessive wear of the sun gear in the planet gear carrier of the main rotor gearbox due to inadequate lubrication from the main rotor gearbox oil pumps with part numbers 7631 955 112 or 7631 955 115.
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Required Actions
Within 100 hours time in service after the effective date, modify the main rotor gearbox oil pump by installing a stronger compression spring (per MBB SB No. 10-16) for P/N 7631 955 115, and replace the pump plunger and install a stronger spring (per MBB SB No. 10-20 and 10-16) for P/N 7631 955 112. Additionally, inspect the magnetic chip detector plug every 10 hours time in service for metallic particles, following MBB instructions if found.
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Compliance Time
Within the next 100 hours time in service after the effective date of this AD, and within the next 10 hours time in service after the effective date and thereafter at intervals not to exceed 10 hours time in service since the last inspection.
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Affected Aircraft
Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C helicopters with main rotor gearbox oil pumps P/N 7631 955 112 or 7631 955 115, having Serial Numbers up to and including 229.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Main Rotor Gearbox
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_77-16-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-16-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters Subject: Main Rotor Gearbox Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/06/1977 Make: Airbus Helicopters Deutschland GmbH Model: BO-105A | BO-105C Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 77-16-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3001 AD NUMBER: 77-16-07 SUBJECT HEADING: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters ACTION: SUMMARY: DATES: Effective September 6, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-16-07 MESSERSCHMITT-BOLKOW-BLOHM (MBB). Amendment 39-3001. Applies to Model BO-105A and BO-105C helicopters which incorporate main rotor gearbox oil pumps, P/N's 7631 955 112 or 7631 955 115, having Serial Numbers up to and including 229. Compliance is required as indicated, unless already accomplished. To prevent excessive wear of the sun gear in the planet gear carrier of the main rotor gearbox, accomplish the following: (a) Within the next 100 hours time in service after the effective date of this AD, modify the main rotor gearbox oil pump as follows: (1) For pumps, P/N 7631 955 115, install a stronger compression spring in accordance with MBB Service Bulletin No. 10-16, dated July 28, 1975, or an FAA-approved equivalent. (2) For pumps, P/N 7631 955 112, replace the pump plunger in accordance with MBB Service Bulletin No. 10-20, dated May 25, 1976, or an FAA-approved equivalent and install a stronger compression spring in accordance with MBB Service Bulletin No. 10-16, dated July 28, 1975, or an FAA-approved equivalent. (b) Within the next 10 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 10 hours time in service since the last inspection, inspect the main rotor gearbox magnetic chip detector plug for the presence of metallic particles. If metallic particles are found, comply with the relevant instructions specified in section 10-1-2 of the MBB BO-105 Maintenance and Overhaul Manual, or an FAA-approved equivalent. (c) An equivalent means of compliance with the requirements in paragraph (b) of the AD, including the initial compliance time and the repetitive inspection interval, may be used in lieu thereof when approved by the Chief, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Region, Federal Aviation Administration, c/o American Embassy, Brussels, Belgium, Tel. 513.38.30. This amendment becomes effective September 6, 1977. FOOTER:
Document Text
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AD Final Rules - DRS_77-16-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-16-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters Subject: Main Rotor Gearbox Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/06/1977 Make: Airbus Helicopters Deutschland GmbH Model: BO-105A | BO-105C Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 77-16-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3001 AD NUMBER: 77-16-07 SUBJECT HEADING: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters ACTION: SUMMARY: DATES: Effective September 6, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-16-07 MESSERSCHMITT-BOLKOW-BLOHM (MBB). Amendment 39-3001. Applies to Model BO-105A and BO-105C helicopters which incorporate main rotor gearbox oil pumps, P/N's 7631 955 112 or 7631 955 115, having Serial Numbers up to and including 229. Compliance is required as indicated, unless already accomplished. To prevent excessive wear of the sun gear in the planet gear carrier of the main rotor gearbox, accomplish the following: (a) Within the next 100 hours time in service after the effective date of this AD, modify the main rotor gearbox oil pump as follows: (1) For pumps, P/N 7631 955 115, install a stronger compression spring in accordance with MBB Service Bulletin No. 10-16, dated July 28, 1975, or an FAA-approved equivalent. (2) For pumps, P/N 7631 955 112, replace the pump plunger in accordance with MBB Service Bulletin No. 10-20, dated May 25, 1976, or an FAA-approved equivalent and install a stronger compression spring in accordance with MBB Service Bulletin No. 10-16, dated July 28, 1975, or an FAA-approved equivalent. (b) Within the next 10 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 10 hours time in service since the last inspection, inspect the main rotor gearbox magnetic chip detector plug for the presence of metallic particles. If metallic particles are found, comply with the relevant instructions specified in section 10-1-2 of the MBB BO-105 Maintenance and Overhaul Manual, or an FAA-approved equivalent. (c) An equivalent means of compliance with the requirements in paragraph (b) of the AD, including the initial compliance time and the repetitive inspection interval, may be used in lieu thereof when approved by the Chief, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Region, Federal Aviation Administration, c/o American Embassy, Brussels, Belgium, Tel. 513.38.30. This amendment becomes effective September 6, 1977. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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